Shaping liquid films by dielectrophoresis

TL;DR

This paper develops a theoretical model and experimental validation for controlling thin liquid film shapes using dielectrophoretic forces generated by surface electrodes, enabling dynamic and complex surface deformations.

Contribution

It introduces a coupled electro-mechanical model for liquid film deformation and demonstrates precise control of film shape through microfabricated electrode patterns.

Findings

Model accurately predicts film deformation based on electrode geometry.

Experimental results show strong agreement with theoretical predictions.

Complex 2D deformations can be achieved and dynamically modulated.

Abstract

We present a theoretical model and experimental demonstration of thin liquid film deformations due to a dielectric force distribution established by surface electrodes. We model the spatial electric field produced by a pair of parallel electrodes and use it to evaluate the stress on the interface through Maxwell stresses. By coupling this force with the Young-Laplace equation, we obtain the deformation of the interface. To validate our theory, we design an experimental setup which uses microfabricated electrodes to achieve spatial dielectrophoretic actuation of a thin liquid film, while providing measurements of microscale deformations through digital holographic microscopy. We characterize the deformation as a function of the electrode-pair geometry and film thickness, showing very good agreement with the model. Based on the insights from the characterization of the system, we pattern conductive lines of electrode pairs on the surface of a microfluidic chamber and demonstrate the ability to produce complex two-dimensional deformations. The films can remain in liquid form and be dynamically modulated between different configurations or polymerized to create solid structures with high surface quality.